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ABSTRACT MAIZE cultivation is widespread throughout the world under a diverse array of climates. These diverse growing habits pose myriad biotic and abiotic threats to successful maize production. Waterlogging (WL) stress, the second most important abiotic constraint after drought, leads to around 25%–30% of production losses each year. Effective identification of suitable donor lines with tolerance against WL and using it in breeding programmes is the main concern for the breeders. The present study focused on the effective and early identification of maize genotypes tolerant to WL based on root traits. For this, 120 maize inbred lines along with Zea mays ssp. parviglumis from different genetic origin were evaluated for WL tolerance both at pre‐emergence as well as the seedling stage at different WL durations, namely, 3, 6 and 9 days to flooding. Results based on percentage germination at pre‐emergence and percentage survival at the seedling stage reveal that germination tolerance is independent of seedling stage tolerance. The chlorophyll content exhibited that the tolerant lines had almost similar levels of chlorophyll at 3 days of flooding with control and subsequent decline recorded in 6 and 9 days. The least reduction in chlorophyll content at 9 days of flooding was found in EML 285. Waterlogging tolerance coefficient (WTC) based on root and shoot traits is higher in tolerant lines than in susceptible ones. Root traits are foremost affected by WL stress and plants cope with such stress by having adaptive mechanisms against it; therefore, the identified lines were further revalidated by the radial oxygen loss (ROL) barrier test, which is an adaptive response under WL stress, which confirmed the line identified under WTC based on root traits, namely, I 185, I 172, LM 16 and teosinte (check), having more than 90% barrier formation corresponds more to the formation of a ROL barrier. These identified lines can be used as parents in hybrid development or deriving the WL‐tolerant lines.
Thapa et al. (Sun,) studied this question.